1. Field of the Invention
The present invention relates to a liquid measuring device which can be used as a proportioner, dispenser or flow meter for a single fluid or for an unlimited number of fluids. The device embodies a free-floating piston sealed within a cylinder capped at both ends with a high-resolution detector system, totally noninvasive to accurately determine the piston location within the cylinder, such detector being coupled to a microprocessor that allows instant changes in volume measurements and flowrate at the touch of a button.
2. Brief Description of the Prior Art
The prior art does not disclose a device which operates in the same manner as the device of this present invention with the high-resolution detector system to accurately determine the location of a piston sealed within a cylinder.
Brobeil, U.S. Pat. No. 2,774,364, discloses a proportioning and dispensing apparatus and method. Although the apparatus permits proportioning by the stroke of a piston it requires a shaft and seal at the end of a cylinder and only permits adjustment by means of cam switches outside of the cylinder.
Brown, U.S. Pat. No. 1,144,583, discloses liquid measuring apparatus in which the quantity of liquid measured is governed by the size of the cylinder. The piston must move the full length of the cylinder and there is no provision for resolution of a portion of a stroke.
Rappl, U.S. Pat. No. 2,687,004, discloses a fluid pressure accessory system for motor vehicles in which both a positive and a negative pump is used in the actuation of accessories.
Johansson, U.S. Pat. No. 3,370,759, discloses a dispenser which only counts complete strokes of the cylinder but does not contain a high-resolution detector.
O'Shei, U.S. Pat. No. 2,345,213, shows a suction pump connected to a cylinder. Schwieger, U.S. Pat. No. 3,289,889, discloses a multiway valve connected between a cylinder and a source. Leach, U.S. Pat. No. 2,995,451, and Clark, U.S. Pat. No. 4,062,373, disclose separate valves for each of a plurality of sources connected to a common mixing chamber.
Murphy, U.S. Pat. No. 3,038,449, discloses a hydraulic control system incorporating a feedback loop to control flow to a piston enclosed within a chamber. Means are provided for sensing the position of the piston (Col. 3, lines 1-2), and this information is used by a control device to regulate on-off valves controlling pressurized fluid sources (Col. 5, lines 24-37). Movement of the piston is not accomplished by suction or pressure provided by a pump, nor is the Murphy apparatus directed to the proportioning of different fluids as in the present invention.
Coppola, U.S. Pat. No. 3,813,990, discloses a hydraulic actuator system comprising hydraulic positioning means including a hydraulically actuated movable output member (piston), a plurality of servovalves for supplying fluid to said positioning means to position the movable output member, feedback means representative of the position of said output member to establish independent servovalve channels for each of said valves, and means for controlling the servovalves in case of malfunction (Col. 3, lines 37-68, and claim 1).
Both Murphy and Coppola disclose devices which will control the operation of valves using feedback means which sense the position of a piston within a chamber. Neither provides for the movement of the piston when the pump pushes or pulls fluid from the cylinder, nor do they cause the piston to expel liquid from either end of the cylinder as a continuous process. In addition, the proportional combining of fluids is not accomplished by either apparatus.